C I completed the same quiz
Answer:
Explanation:
From the question we are told that mass
Thin layer radius 
Generally the expression for ths solution is given as
Xcm =(m*0 =m(-2R))/2m =-mR/(2m)=-R/2
the center of mass will not move at initial state
Considering the center of mass of both bodies


Therefore the enclosing layer moves
Please elaborate more on your question so I can help you
No friction present means: Ek = Ep
So Ek = mgh = 10 * 9.8 * 2 = 196 J
The outside observer, at rest relative to the spaceship, would see the spaceship
get shorter. and the clocks on the spaceship run slower than they should.
At the same time, the crew of the spaceship, looking back at the observer on
Earth, would see the observer on Earth get shorter, and the observer's clock
run slower than it should.
They would both be measuring what they see correctly.